#include <iostream>
#include <vector>
using namespace std;

vector<int> frequencyOfMaxValue(vector<int>& numbers, vector<int>& queries) {
    int n = numbers.size();
    vector<int> answer(n, -1);   
    int maxvalue = -1;           
    int count = 1;              
    for (int i = n - 1; i >= 0; --i) {
        if (numbers[i] == maxvalue) {
            count++;
        } else if (numbers[i] > maxvalue) {
            maxvalue = numbers[i];
            count = 1;
        }
        answer[i] = count;       
    }

    vector<int> result;
    for (int index : queries) {
        result.push_back(answer[index - 1]);  
    }

    return result;
}

#include <bits/stdc++.h>
using namespace std;
vector<int> getPopularityOrder(vector<vector<int>> song_preferences) {
    int n = song_preferences[0].size();
    vector<vector<int>> boxScore(n, vector<int>(n, 0));
    for (const vector<int>& pref : song_preferences) {
        for (int i = 0; i < pref.size() - 1; i++) {
            for (int j = i + 1; j < pref.size(); j++) {
                boxScore[pref[i]][pref[j]] += 1;
            }
        }
    }

    vector<array<int, 2>> wins(n, {0, 0});
    for (int i = 0; i < n; i++) {
        wins[i][0] = i; 
        for (int j = i + 1; j < n; j++) {
            int score = boxScore[i][j] - boxScore[j][i];
            if (score >= 0) {
                wins[i][1]++;
            } else {
                wins[j][1]++;
            }
        }
    }

    sort(wins.begin(), wins.end(), [](const array<int, 2>& a, const array<int, 2>& b) {
        if (a[1] == b[1]) {
            return a[0] < b[0];
        } else {
            return b[1] < a[1];
        }
    });

    vector<int> result;
    for (const auto& win : wins) {
        result.emplace_back(win[0]);
    }

    return result;
}

def find_smallest_k(mat, n):
    for k in range(n):
        row_condition = all(mat[k][j] == 0 for j in range(n) if j != k)
        column_condition = all(mat[i][k] == 1 for i in range(n) if i != k)
        
        if row_condition and column_condition:
            return k
            
    return -1
n = int(input())
mat = []
for _ in range(n):
    mat.append(list(map(int, input().split())))
result = find_smallest_k(mat, n)
print(result)

class Node:
    def __init__(self, key):
        self.data = key
        self.left = None
        self.right = None
def build_tree(level_order):
    if not level_order or level_order[0] == -1:
        return None
    
    iter_order = iter(level_order)
    root = Node(next(iter_order))
    queue = [root]
    
    while queue:
        current_node = queue.pop(0)
        left_value = next(iter_order, -1)
        right_value = next(iter_order, -1)
        
        if left_value != -1:
            current_node.left = Node(left_value)
            queue.append(current_node.left)
        
        if right_value != -1:
            current_node.right = Node(right_value)
            queue.append(current_node.right)
    
    return root
def largest_bst_subtree(root):
    def post_order(node):
        if not node:
            return (float('inf'), float('-inf'), 0, True)
        left_min, left_max, left_size, left_is_bst = post_order(node.left)
        right_min, right_max, right_size, right_is_bst = post_order(node.right)
        if left_is_bst and right_is_bst and left_max < node.data < right_min:
            total_size = left_size + right_size + 1
            return (min(left_min, node.data), max(right_max, node.data), total_size, True)
        else:
            return (0, 0, max(left_size, right_size), False)
    return post_order(root)[2]
input_list = list(map(int, input().split()))
height = input_list[0]
level_order = input_list[1:]
root = build_tree(level_order)
if not root:
    print(-1)
else:
    result = largest_bst_subtree(root)
    print(result)

def minStrength(matrix):
    if not matrix or not matrix[0]:
        return 0
    
    rows, cols = len(matrix), len(matrix[0])
    dp = [0] * cols
    
    dp[-1] = 1 if matrix[-1][-1] > 0 else -matrix[-1][-1] + 1
    
    for j in range(cols - 2, -1, -1):
        dp[j] = max(dp[j + 1] - matrix[-1][j], 1)
    
    for i in range(rows - 2, -1, -1):
        dp[-1] = max(dp[-1] - matrix[i][-1], 1)
        for j in range(cols - 2, -1, -1):
            min_path = min(dp[j], dp[j + 1])
            dp[j] = max(min_path - matrix[i][j], 1)
    
    return dp[0]

import heapq

def finalIndex(N, A):
    dist = [float('inf')] * (N + 2)
    dist[N] = 1 
    dist[N + 1] = 0 
    pq = [(1, N)]  

    while pq:
        d, node = heapq.heappop(pq)
        
        if d > dist[node]:
            continue

        if node == 1:
            break
       
        prev = node - 1
        if prev >= 1 and d + 1 < dist[prev]:
            dist[prev] = d + 1
            heapq.heappush(pq, (dist[prev], prev))

        prev = A.index(node) + 1
        if d + 1 < dist[prev]:
            dist[prev] = d + 1
            heapq.heappush(pq, (dist[prev], prev))

    return sum(dist[1:N+1])

#include <bits/stdc++.h>
using namespace std;
class UnionFind {
public:
    UnionFind(int n) : parent(n), rank(n, 0) {
        for (int i = 0; i < n; ++i) {
            parent[i] = i;
        }
    }

    int find(int u) {
        if (parent[u] != u) {
            parent[u] = find(parent[u]); 
        }
        return parent[u];
    }

    void unionSet(int u, int v) {
        int rootU = find(u);
        int rootV = find(v);
        if (rootU != rootV) {
            if (rank[rootU] > rank[rootV]) {
                parent[rootV] = rootU;
            } else if (rank[rootU] < rank[rootV]) {
                parent[rootU] = rootV;
            } else {
                parent[rootV] = rootU;
                ++rank[rootU];
            }
        }
    }

    bool sameSet(int u, int v) {
        return find(u) == find(v);
    }

private:
    vector<int> parent;
    vector<int> rank;
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, m1, m2;
    cin >> n >> m1 >> m2;

    UnionFind ufAlice(n + 1); 
    UnionFind ufBob(n + 1);   

    vector<pair<int, int>> connectionsAlice(m1);
    vector<pair<int, int>> connectionsBob(m2);

    for (int i = 0; i < m1; ++i) {
        int u, v;
        cin >> u >> v;
        connectionsAlice[i] = {u, v};
        ufAlice.unionSet(u, v);
    }

    for (int i = 0; i < m2; ++i) {
        int u, v;
        cin >> u >> v;
        connectionsBob[i] = {u, v};
        ufBob.unionSet(u, v);
    }

    int maxConnections = 0;
    for (int u = 1; u <= n; ++u) {
        for (int v = u + 1; v <= n; ++v) {
            if (!ufAlice.sameSet(u, v) && !ufBob.sameSet(u, v)) {
                maxConnections++;
                ufAlice.unionSet(u, v);
                ufBob.unionSet(u, v);
            }
        }
    }

    cout << maxConnections << endl;
    return 0;
}

c++ 
#include <bits/stdc++.h> 
using namespace std; 
#define ll long long 

ll mod = 1e9 + 7, cc_total = 0; 

void dfs(vector<ll> adj[], vector<bool> &visited, ll src) 
{ 
    if (visited[src]) 
        return; 
    cc_total++; 
    // cout << src << " " << cc_total << "  vis\n"; 
    visited[src] = true; 
    for (auto i : adj[src]) 
    { 
        dfs(adj, visited, i); 
    } 
} 

void solve() 
{ 
    int n, m, x, y, total = 0, cap = 1; 
    cin >> n >> m; 
    vector<ll> adj[n + 1]; 
    vector<bool> visited(n + 1, false); 
    // for (int i = 1; i <= n; i++) 
    // { 
        // adj[i].push_back(i); 
    // } 
     
     
    for (int i = 0; i < m; i++) 
    { 
        cin >> x >> y; 
        adj[x].push_back(y); 
        adj[y].push_back(x); // for undirected 
    } 

    for (int j=1; j<=n; j++) 
    { 
        // for (auto j : i) 
        { 
            if (!visited[j]) 
            { 
                cc_total = 0; 
                dfs(adj, visited, j); 
                total++; 
                 
                cap = (cc_total*cap)%mod; 
                total %= mod; 
                // cout << endl; 
                cc_total = 0; 
            } 
        } 
    } 
    cout << total << " " << cap << "\n"; 
} 
int main() 
{ 
    int t = 1; 
    // #ifndef ONLINE_JUDGE 
    // freopen("input.txt", "r", stdin); 
    // freopen("output.txt", "w", stdout); 
    // #endif 
    cin >> t; 
    while (t--) 
    { 
        solve(); 
    } 
    return 0; 
} 

#include <bits/stdc++.h>
using namespace std;
int solve(const string& str) {
    if (str.empty()) return -2;
    
    int maxInt = -1;
    int currentNumber = 0;
    bool hasNumber = false;

    for (char ch : str) {
        if (isdigit(ch)) {
            currentNumber = currentNumber * 10 + (ch - '0');
            hasNumber = true;
        } else {
            if (hasNumber) {
                maxInt = max(maxInt, currentNumber);
                currentNumber = 0;
                hasNumber = false;
            }
        }
    }

    if (hasNumber) {
        maxInt = max(maxInt, currentNumber);
    }

    return maxInt == -1 ? -1 : maxInt;
}

int main() {
    int n;
    cin >> n;  
    cin.ignore();  

    string str;
    getline(cin, str);  

    cout << solve(str) << endl;

    return 0;
}